The present invention relates to an auto-focus lens module, especially to a lens module that uses electromagnetic force as well as spring force as driving force to control movement of the lens for auto-focusing.
Either digital cameras or mobile phones with shooting function are disposed with a lens module that includes stepless type or two-step auto focusing type. However, structure of conventional lens module is still quite complicated with quite large volume, against the principle of compact design. Moreover, spring blades are used to balance the electromagnetic force while the spring blades are easy to be deformed by external forces such as vibration, rebounding or after being used for a long time so that the stability and accuracy of the movement of the lens holder have been affected. The inventor of the present invention has applied U.S. patent application Ser. Nos. 11/284,880, 11/385,791 and application Ser. No. 11/484,674, wherein a coil is sleeved between a lens and a coiled spring. That means the coiled spring is outside the coil so that the distance between the coil and the magnets is increased and the electromagnetic force generated therebetween is reduced. Moreover, the coiled spring is sleeved outside the coil so that the diameter of the coiled spring is larger compared with the coil Thus balance and stability of the coiled spring have been affected. Therefore, there is still a space for improvement.